redridge

this is the reason why you would want the fan mod....

Macster

You can't say that with any certainty. The in-dash temp gage is at best a rough indicator of the coolant's temperature.

After I ran through AZ in 116F heat and ran with the coolant at 226F for miles and intake temp at 135F -- even the engine compartmant fan appeared to be running non-stop -- I checked with my local Porsche dealer service department and he checked with the factory and the word back was as long as there were no warning lights on or flashing the engine was ok, suffered no overheating.

That was years ago and over 100K miles ago and apparently the engine was not affected at all.

Thankfully I had relatively refresh Mobil 1 0w-40 oil in the engine having had it changed just 1000 miles prior to ending up in the AZ heat.

I have checked the gage's position relative to the actual coolant temperature and roughly every needle width after 180 is another 10 degs of coolant temp.

But these in-dash temp gages vary considerably in how the react to coolant temperature signals from the coolant temp sensor. Porsche (as is true with most automakers) purposely fit dampened gages to avoid wide swings in the needle's travel to avoid scaring the owners.

The most important thing is the engine's cooling system must remain pressure tight. Any leak, even a cap leak that allows pressure to escape can under high heat conditions allow localized overheating and this can quickly damage the engine.

But as long as the cooling system can maintain pressure under high operating temperature conditions the engine's safe. It is the pressure that plays a major role in controlling any possibility of the coolant flashing to steam at the hottest locations in the engine.

Also, one should periodically check the function of the radiator fans. My 02 Boxster's passenger fan stopped working cause the low speed ballast resistor failed.

There's sufficient margin to get by on one fan but of course the non-functioning fan should be made functional again as soon as possible.

I've cleaned the radiator ducts out several times -- lots of trash -- but never found the engine's cooling any different after than before. The major concern from the presence of trash is corrosion.

Sincerely,

Macster.

Eharrison

^^^^So is there a quick check to see if both fans are working?

white99c2

I woke up really early and did the radiator fan mod complete with switch, works like a charm. I did the engine fan mod without a switch for now, it turns on with the key.

The forecast was 115 today and I wanted to combat it. Got a new radiator cap-check, cleaned radiators-check, switched from coolant/water to distilled water/Water Wetter-check and now the fan mod front and rear.

This morning at 8AM it was a balmy 100 degrees here, drove to work the climate control display trick showed 100C, thats 212F when I got to work. The temp gauge was in the middle of the zero in 180....SUCCESS.
Drove home in 115 heat a few minutes ago and the temp gauge was climbing higher and higher just past the 3/4 mark. The climate control trick shows 113C thats 235F, YIKES THATS A NEW RECORD.

I read some other guys post and he said he wished his car didn't have a temperature gauge so do I.

I have another 12 ounce bottle of Water Wetter and I'm going to add it tomorrow morning after I use a turkey baster to suck out some water from the expansion tank.

I feel like all of this work, time and energy has accomplished nothing. I'm renaming the 996 INFERNO.

Ubermensch

I've been having similar issues. I did a three day track event this week and the temperatures were running higher than usual (108-112C). I was a little concerned and figured it was old radiators not doing their job. Then I noticed that just cruising around was generating high temperatures. I almost over heated on the drive home when stuck in an hour of traffic at 90F ambient. I'm starting to diagnose things now. It seems like my driver side fan isn't coming on even at 107C coolant temperatures. The ballast resistor looks easy to replace. Is there a easy way to check it's functionality before replacing it?

white99c2

Mike, it was 91 in Coral Springs today and 115 here. The thermostat is working fine, it kicks in right at 185 degrees, the air discharge from the radiator fans under the sides of the front bumper gets HOT at 185 and gets hotter and hotter so the thermostat is opening and sending the water to the radiators.

I think I'm going to start a post and ask others in Phoenix what temps their 996's are running at. Like I said at 100 this morning my car stayed steady at 212F and the gauge was in between the 8 and the 0 in 180.

ivangene

have you checked the water pump?

we had a run of about 4 or 5 water pumps this last week... all were missing fins on the impellers... hell, one was missing the impeller.... hard to move water with a round bushing...

you might be a candidate for new water pump and LNE's lower temp thermostat (which I have said in the past I dont fully understand the benefit without the fans kicking in at lower temps, so with the fan mod you should be good)

LJpete

Edit: It was 98 degrees yesterday when I drove home and my car was a constant between the 8 and the 0 but never went further than the 0. Even in stop and go portion of my commute.

chsu74

There are two stages of fan speed. Does yours turn on high? A/C only kicks it in low forst.

Ubermensch

Any easy way to diagnose this, short of taking the pump off?

S.

Macster

There are two tests one can perform. Test #1 is to drive the car until engine/drivetrain fully up to operating temperature. The AC wants to be off.

At some point -- if the ambient temperature high enough and my experience is it does not take real hot day (mid to high 708 plenty hot enough) -- the fans should come on. They come on when the coolant's temperature reaches 212F.

The fans come on low speed and run until the coolant temperature drops to 205F. Now you might even with the engine up to temperature raise the engine speed with the car stopped and the transmission in neutral. Run rpms up to 2K or so (higher is not necessary) and hold for 10 to 15 seconds. This will increase the coolant's temperature to the point the fans should come on.

Under very high temperature conditions if the coolant temperature climbs higher -- 216F is my info -- the fan speed should switch to high speed.

What you want to do is verify both fans come on low speed and run and then shut off as the coolant temp drops from the fans running. Do not rely upon your ears alone. Get out of the car and verify you can feel air flowing into the radiator ducting and out again. My 03 Turbo lost a radiator fan hub/blade assembly. Shaft snapped. The electric motor ran but no air flowed through the radiator. So check that you can actually feel air and air flow through both radiator ducts should be the same as best as you can tell.

This verifies fan operation, air flow through the radiators, t-stat operation, water pump operation, and to some extent the ability of the cooling system to maintain pressure. (Doing this above test caused pressure to build to the point the coolant tank in my 02 Boxster split (I suspected it was cracked to begin with). But at least the tank failed while the car in my driveway and not out on the road. BTW, the tank failed at around 233K miles...)

Once you are sure the fans come on and go off based on coolant temperature, you can when the fans are off then switch on the AC. Both fans should come on and remain on regardless of the coolant's temperature.

Sincerely,

Macster.

jrgordonsenior

Sdie bar: You guys running in hottler climates (like hell, Az) should consider using a heavier oil than 0-40 during these hot months. At least 5-40, but 15-50 or straight 40 would be better....

white99c2

I switched to 15-50 this last change last month. The pressure stays high for about 5 miles or so until it heats up and thins out a bit.

Macster

IIRC neither 15w-50 or straight 40 weight oil approved by Porsche.

Mobil 1 0w-40 a bit "thin" (its HTHS numbers lower than comparable oils) but given reasonable oil/filter service intervals (5K miles) the engine should be just fine. I've run through some mighty hot areas in my 02 Boxster with Mobil 1 0w-40 and the engine has not suffered any. And the engine has over 233K miles on it. But I change the oil/filter every 5K miles.

(I've since switched to Castrol Syntec 5w-50 oil cause I think Mobil has cut back the quality of its oils.)

If one didn't want to use Mobil 1 0w-40 or Castrol 5w-50 (or Mobil 1 5w-50 -- not a typo for 15w-50) there are several other brands of quality oils to chose from that come in the 5w-40 multi-viscosity grade and would be fine and are approved by Porsche.

Sincerely,

Macster.

jrgordonsenior

I don't wish to spar with someone who gives as much to these forums as you do but..... Porsche's viscosity recommendations are not necessarily in the best interests of folks living in the deserts. They're more in keeping with their capitulation to the anti-racing greenies of Europe.

I have a friend who teaches Porsche racing in Dubai. I just wrote him to ask what viscosity they're using over there in their factory supported GT3's and RSR's. I'd be surprised if it's 0-40....